1. Field of the Invention
The present invention relates generally to a digital broadcasting system and a method for transmitting and receiving electronic service guide data in a digital broadcasting system, and more particularly to such a system which communicates applications capable of executing content files downloaded through a file download service.
2. Description of the Related Art
Transmission technologies for digital broadcasting are for various broadcasting systems, such as a Digital Audio Broadcasting (DAB), a Digital Video Broadcasting (DVB), and a Digital Multimedia Broadcasting (DMB). As an example, the DVB system, which is a European Digital Video Broadcasting technology, is a transmission standard that supports mobile and digital multimedia services for mobile and hand-held devices, as well as existing digital broadcastings.
In the DVB system, it is possible to multiplex and simultaneously transmit Moving Picture Experts Group-2 (MPEG2) Transport Stream (TS)-based data and Internet Protocol (IP)-based data stream, and it is also possible to multiplex and transmit several services into one IP stream. A receiver receives data of the IP stream from a transmitter, demultiplexes the data into individual services, decodes TS packets of a desired service and outputs the decoded data onto a screen for the user. At this time, the user needs to know which various services are provided in the DVB system and which contents the respective services include.
In the DVB system, Electronic Service Guide (ESG) is used for communicating information on respective services. The ESG provides users with various services, such as communicating information on current programs and information on programs by channel or time, and showing purchase information on corresponding programs to users. This ESG has a purpose of allowing users to select various services and related contents. In order to provide the ESG service in digital broadcast standard, ESG data models based on XML (eXtensible Markup Language) have been defined in ETSI (European Telecommunications Standards Institute). The ESG data models are easy to flexibly extend in DMB receiving terminals.
FIG. 1 illustrates a configuration of conventional ESG data.
The ESG data models defined in ETSI are classified into XML fragments, such as Service, Access, Schedule, Contents, PurchaseItem, PurchaseData and PurchaseChannel.
The service fragment defines information related to respective channels and the schedule fragment defines schedule information on contents to be transmitted to specified channels. The contents fragment includes information on contents to be transmitted to the respective channels. The access fragment defines information on channels to which specified services are transmitted, thereby allowing the receiver to find and provide for specified services when the user selects them.
The PurchaseItem includes information on service bundles, and is connected with the PurchaseData and the PurchaseChannel so as to transfer purchase information on services. The fragments have connection chains between them to form the overall ESG data.
There may be other fragments included in the XML fragments, such as PreviewData, Interactivity Data, Service Guide Delivery Descriptor and Session Description.
Meanwhile, an Open Mobile Alliance (OMA) broadcasting service defines a file download service, and provides one channel as a file download only channel. The file download service indicates that when the ServiceType in the service fragment of the digital broadcasting is defined as the file download service, the file downloads are provided from the corresponding channel to the receiver.
However, neither extensions nor types of download files are defined in the digital broadcast standard. Thus, it cannot be recognized which applications are suitable for the downloaded files, but it should be analogized only from file names. It is difficult to accurately identify the suitable application solely from a MIME (Multi-purpose Internet Mail Extensions) type presented in the digital broadcast standard or the file extensions. When the receiver can't connect the download files to correct applications, the user cannot receive desired services.
Hence, the transmitter should specify which applications are suitable for the download files, and the receiver should execute the files by using the specified applications, in order to provide the user with stable services.
The digital broadcasting file download service is provided for more than allowing files to be received through the broadcasting channel or an interaction channel and storing the downloaded files. By providing additional information related to the digital broadcasting service as a file unit or providing additional services using the file download, the file download service in the digital broadcast standard provides the user with differentiated broadcasting services. In order to allow the user to conveniently and reliably use such services, the use of the downloaded files should be clearly described so that the files are correctly executed.
In the current digital broadcast standard, it is not specified how to identify applications for the downloaded files, and it is not described how to use the MIME type or the extension of files on the digital broadcast standard. So, there is a need for directions on how to service the download files.
In addition, although the file type can be recognized from the MIME type or name of the files, these are insufficient to specify programs connected to services in the file download service since files of the same type may be executed in different services.
If, for example, an audio file is downloaded, the file can be recognized as being an audio file just from the MIME type or name thereof. However, it is difficult to know whether the file is merely provided as an additional mp3 file or is a file for a ringtone service. Therefore, there is a need to specify applications for the files in the file download service.